Ok, I asked this last week but I've been gone for a week and I'm about to get this thing in the mail tomorrow.

I need to know whether I have to remove the air pump and acv or not. This is what it says on Racingbeat.com

"The down pipe is equipped with an exhaust back-pressure tube for correct operation of the 6-port actuators. Installation of this requires the removal of the air control and check valve and the air pump."

It comes with the blockoff plates so I can remove it, but what is going to happen if I remove it. I know it is supposed to dump air into the exhaust but why would I need to remove it for the new exhaust let the 5/6 ports work???

 

strange.. the 5/6 ports work off the airpump somehow i believe (i cant answer that; their function off the air pump is still foreign to me). seems funny to have no cat, but a smog pump. makes sense for the actuators, though. there's other ways to open the sleeves, but thats some extra work. its been covered before somewhere on this site. electronicly controlled.

 

on the site it says: "for correct operation of the 6-port actuators. Installation of this requires the removal of the air control and check valve and the air pump"

The back pressure is what I've been told causes the actuators to move. So I don't know what's going on.

 

i believe the backpressure is for S4 models whereas the pump is used on S5 models.

 

ok, I'm just going to leave everything in place and when I put the new pipe in I'll check to see if the actuators are still working, I guess that's good enough. If not I'll remove the stuff.

 

remember, theres a long tube that goes down to the cat. without a cat, the tube has nowhere to go (unless you weld a 'nipple' on there and pump useless air into the exhaust).

 

That's what I've been talking about, the presilencer I'm getting has that pipe and that's what has been confusing me this whole time, it says I have to remove the airpump for the ports to work, I though the sensing for the ports was off of that tube. Split air pipe if we want to name it

 

If you dont want to have the split air pipe anymore that comes from the cat (since you're replacing it with a presilencer), hook the actuators up to the air pump pipe that goes to the acv, or the acv relief line, that will supply enough pressure to open them

 

no, the RB presilencer I'm getting is made for the s4 so it has a split air pipe coming off of the presilencer, so it should be fine if I replace the stock cat with this system.

My question is that outwardly this looks like it should not function any different than the stock system so why would it need the air pump and acv removed.

 

When I bought my S4 N/A Racing Beat down pipe and presilencer, I asked the same question. After the question was posed to a Racing Beat Tech, not a sales person, I was told you don’t need to remove the air pump or associated components. So, down pipe and presilencer were installed as a straight pre-cat and cat replacement without changing anything else and it works fine. Reasons I did this: 1. Since the RB presilencer is slightly longer than the main cat, a custom spacer block could be cut allowing for easy switch out of the main cat and presilencer, if needed. 2: Didn’t feel removing air pump, although not needed on an S4, would yield significant HP. 3. Didn’t want to put a dual pulley on the alternator, if the air pump was removed.

 

you can keep the air pump ... air pump on s4 is used for emissions and anti-afterburn ... You need to connect the split air pipe the RB silencer so that you get the bacj pressure needed to open the 5/6 ports.

I think what RB is trying to say is that since you don't have a cat anymore, the air pump is not needed anymore, which btw is kinda wrong, you still need it for anti-afterburn purposes ... in any case, you certainly don't have to take it out.

Hugues -